1. Field of the Invention
The present invention relates to a transmission method for a multiple antenna system, and more particularly, but not exclusively, to a power-saving transmission method.
2. Discussion of Related Art
A multiple antenna system which is attracting attention as primary technology for a next-generation wireless communication system has advantages of being able to improve communication reliability using a plurality of independent transmission paths and increase a communication transfer rate using an independent spatial channel. These advantages are associated with diversity gain and multiplexing gain, respectively. These two gains coexist and have a diversity-multiplexing tradeoff (DMT) relationship wherein when one of the gains increases, the other decreases. Related technology includes a technique of switching among multiple-input multiple-output (MIMO) transmission schemes in view of a DMT relationship and a channel state to maximize a data transfer rate.
Meanwhile, the multiple antenna technology having the above advantages is even being applied to ubiquitous networking using compact mobile wireless devices (i.e., mobile devices). Since most mobile devices are powered by batteries, they have a limited operation time and inconveniently require charging or changing of the batteries.
Accordingly, there is a need for a power-saving transmission method in a multiple antenna system having limited energy.